WO2021098960A1

WO2021098960A1 - Hill assist/brake hold vehicle drive off strategy

Info

Publication number: WO2021098960A1
Application number: PCT/EP2019/081963
Authority: WO
Inventors: Felipe SANTAFE
Original assignee: Toyota Motor Europe
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2021-05-27

Abstract

A method of accelerating a vehicle (1), comprising modulating a braking torque (BT) of the vehicle based on an evolution in a driving torque (DT) delivered to a drive component (5) of the vehicle such that the braking torque is modulated inversely to the evolution of the driving torque. A vehicle configured to carry out same.

Description

HILL ASSIST/BRAKE HOLD VEHICLE DRIVE OFF STRATEGY

FIELD

[0001] The present disclosure relates to the field of vehicle control. BACKGROUND ART

[0002] A driver of a vehicle may lack proper skill and technique to accelerate the vehicle, for example when the vehicle is accelerated in an uphill direction from a standstill on the incline. It is known to provide hill assistance to a vehicle in order to facilitate control of the vehicle in such circumstances, for example by deferring cessation of braking action to reduce instances of downhill motion of the vehicle.

SUMMARY

[0003] The inventors have recognized that sustaining braking during acceleration can interfere with one or more desired vehicle behaviors. To resolve this problem, a method may be provided, according to examples of the present disclosure, of accelerating a vehicle, comprising modulating a braking torque of the vehicle based on an evolution in a driving torque delivered to a drive component of the vehicle such that the braking torque is modulated inversely to the evolution of the driving torque. [0004] Such a method may allow for prevention or reduction of downhill movement while limiting or reducing interference with one or more desired vehicle behaviors. [0005] The drive component may be or include a drive axle of the vehicle.

[0006] The method may comprise increasing the braking torque in response to the driving torque decreasing. Additionally or alternatively, the method may comprise reducing the braking torque in response to the driving torque increasing.

[0007] The braking torque may be modulated based on the evolution in the driving torque such that a sum of a braking force and a driving force is greater than or equal to a first predetermined value.

[0008] The braking force may correspond at least partially to the braking torque.

[0009] The driving force may correspond at least partially to the driving torque.

[0010] The method may comprise determining the first predetermined value based on a rollback force on the vehicle.

[0011] The rollback force may correspond at least partially to a rollback torque on the drive component.

[0012] The driving torque may correspond to a motor torque and a transmission capacity. The method may comprise determining whether, in view of the transmission capacity, the driving force is equal to or within a predetermined range of a second predetermined value. The second predetermined value may be greater than or equal to the first predetermined value. The method may comprise adjusting the motor torque when the driving force is determined to be not equal to or not within the predetermined range of the second predetermined value. The motor torque may be adjusted so that the driving force approaches the second predetermined value.

[0013] The transmission capacity may correspond at least to an engagement factor of a clutch of the vehicle.

[0014] The method may comprise determining the second predetermined value based on one or more of the following: the transmission capacity, the first predetermined value, a speed of the drive component.

[0015] The motor torque may correspond to a motor input signal and a motor assist signal. The step of adjusting the motor torque may include applying the motor assist signal to supplement the motor input signal in order to increase the motor torque. [0016] The step of adjusting the motor torque may include applying the motor assist signal to supplement the motor input signal in order to increase the driving torque such that the driving force increases to or above the first predetermined value.

[0017] The motor torque may correspond to a motor input signal and a motor assist signal. The step of adjusting the motor torque may include applying the motor assist signal to diminish the motor input signal in order to reduce the motor torque.

[0018] The method may comprise attenuating the motor assist signal in response to one or more of the following: a speed of the drive component meeting or exceeding a predetermined first speed value, the motor input signal falling below a predetermined first motor value or being not determinable, the transmission capacity falling below a predetermined first transmission value or being not determinable, a brake input signal being detected at or above a predetermined first brake value or being not determinable, a predetermined motor behavior being detected.

[0019] The method may comprise increasing the braking torque in response to the speed of the drive component falling below a second speed value.

[0020] The step of increasing the braking torque in response to the speed of the drive component falling below the second speed value may be performed subsequent to an onset of attenuation of the motor assist signal.

[0021] The step of determining whether the driving force is equal to or within the predetermined range of the second predetermined value and the step of adjusting the motor torque are performed when the transmission capacity exceeds a third predetermined value.

[0022] The method may comprise determining the third predetermined value based on one or more of the following: the first predetermined value, a gear ratio between the motor and the drive component.

[0023] According to examples of the present disclosure, a vehicle may be provided. The vehicle may be configured to carry out a method according as described earlier herein.

[0024] Such a vehicle may provide for downhill movement to be reduced or prevented during acceleration in an uphill direction from a standstill on an incline, while limiting or avoiding interference with one or more desired vehicle behaviors.

[0025] The vehicle may comprise one or more of the following: means for determining a state and/or behavior of a motor of the vehicle, means for determining a speed of a drive component of the vehicle, means for determining a transmission capacity and/or a gear ratio between the motor and drive component, means for determining a motor input signal, means for determining a rollback torque of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS [0026] The disclosure may be more completely understood in consideration of the following detailed description of aspects of the disclosure in connection with the accompanying drawings, in which:

[0027] Figure 1 shows a schematic representation of a vehicle;

[0028] Figure 2 represents driving force (Plot 2A) and braking force (Plot 2B) over time;

[0029] Figure 3 represents driving torque (Plot 3A), braking torque (Plot 3B), vehicle speed (Plot 3C), transmission capacity (Plot 3D), motor behavior (Plot 3E), and motor input signal (Plot 3F) over time;

[0030] Figure 4 represents driving torque (Plot 4A), transmission capacity (Plot 4B), and vehicle speed (Plot 4C) over time;

[0031] Figure 5 represents driving torque (Plot 5A), transmission capacity (Plot 5B), and vehicle speed (Plot 5C) over time.

[0032] The term "exemplary" is used in the sense of "example," rather than "ideal." While aspects of the disclosure are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular embodiment(s) described. On the contrary, the intention of this disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

DETAILED DESCRIPTION [0033] As used in this disclosure and the appended claims, the singular forms "a",

"an", and "the" include plural referents unless the content clearly dictates otherwise. As used in this disclosure and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. [0034] The following detailed description should be read with reference to the drawings. The detailed description and the drawings, which are not necessarily to scale, depict illustrative aspects and are not intended to limit the scope of the disclosure. The illustrative aspects depicted are intended only as exemplary.

[0035] Figure 1 represents a vehicle 1 according to an example of the present disclosure. The vehicle may be a manual transmission vehicle, for example. [0036] The vehicle 1 may be configured to carry out a method of accelerating a vehicle.

[0037] The method may comprise modulating a braking torque of the vehicle 1.

[0038] The braking torque may be understood to be a torque provided by the vehicle 1 in opposition to movement of the vehicle. For example, the braking torque may be provided to one or more wheels 2, 3 of the vehicle via a brake 4. The braking torque may be provided directly to the wheel(s) 2, 3, and/or via one or more components connected thereto.

[0039] The braking torque may be modulated by increasing and/or decreasing braking intensity. For example, when one or more friction brakes are used for providing braking torque, the braking torque may be modulated by increasing and/or decreasing friction forces between braking surfaces (such as pads and rotors, or shoes and drums, for example). This may be done via changes in contact forces between the braking surfaces, for example. Interactions between the vehicle 1 and its environment (such as an interaction between a wheel 2, 3 and the ground/road surface during application of a friction brake connected to the wheel) convert the braking torque into a braking force tending to oppose movement of the vehicle.

[0040] The vehicle 1 may comprise means for determining the braking torque. For example, the vehicle 1 may include one or more sensors 41 for measuring braking intensity. For example, the one or more sensors may measure friction and/or contact forces of one or more friction brakes of the vehicle (if present). The vehicle 1 may comprise means for calculating the braking force corresponding to the determined braking torque. For example, the vehicle 1 may include a model of the friction brake which may be applied to the measured braking intensity to determine the braking torque, and may include a model of a wheel connected to the friction brake which may be applied to the braking torque to calculating the braking force.

[0041] The vehicle 1 may comprise means for modulating the braking torque according to a brake assist signal, which may be as part of or in addition to a brake input signal. The brake assist signal may, for example allow for the braking torque to be increased and/or decreased relative to a value corresponding to the brake input signal. As a non limiting example, the brake input signal may correspond to a position of a brake pedal 45 of the vehicle 1 (when present). The vehicle 1 may comprise a sensor 43 for measuring the brake input signal (for example via the position of the brake pedal 45), for example, in addition or as an alternative to the sensor(s) 41 for measuring braking intensity described above.

[0042] The braking torque may be modulated based on an evolution in a driving torque delivered to a drive component 5 of the vehicle 1.

[0043] The drive component 5 of the vehicle 1 may be coupled in rotation to, or include one or more wheels 2, 3 of the vehicle. At least one of these wheels may be a drive wheel 3 of the vehicle, for example.

[0044] For example, the drive component 5 may include a portion of the drivetrain of the vehicle 1 that is arranged kinematically between a clutch 6 of the vehicle and a drive wheel 3 of the vehicle, and/or may include a drive wheel connected to such a portion of the drivetrain. For example, the drive component 5 may be or include a drive axle to which the drive wheel 3 is coupled in rotation.

[0045] The driving torque may be understood to be a torque provided by the vehicle 1 to produce movement of the vehicle. For example, the driving torque may be provided to one or more drive wheels 3 of the vehicle 1, including or via the drive component 5. Interactions between the vehicle 1 and its environment (such as an interaction between the drive wheel 3 and the ground/road surface, for example) convert the driving torque into a driving force tending to move the vehicle in a direction of travel. [0046] The vehicle 1 may comprise means for determining the driving torque. For example, the vehicle 1 may comprise a sensor 51 for measuring the driving torque directly. The vehicle 1 may comprise means for calculating the driving force corresponding to the determined driving torque, for example. For example, the vehicle 1 may include a model of the drive wheel(s) 3 which may be applied to the measured driving torque to calculate the driving force.

[0047] The vehicle 1 may comprise a motor 7 to produce the driving torque, for example. The motor 7 may include, for example, an internal combustion engine 71. [0048] The vehicle 1 is represented on a surface so as to be inclined by an inclination amount Q with respect to horizontal. Gravitational forces therefore contribute to a "rollback force". The term "rollback force" may be understood to mean a force tending to oppose movement of the vehicle 1 up an incline. For example, when the vehicle 1 is made to move in a reverse direction up the incline, the rollback force may encourage the vehicle to move in a forward direction. Additionally or alternatively, when the vehicle 1 is made to move in the forward direction up the incline, the rollback force may encourage the vehicle to move in the reverse direction.

[0049] The rollback force may additionally tend to move the vehicle 1 down the incline. By canceling out or overcoming the rollback force (for example by generating sufficient braking force and/or driving force), movement of the vehicle 1 down the incline may be avoided.

[0050] Plot 2A of Figure 2 shows a plot of driving force "DF" over time for the vehicle 1 shown in Figure 1. The driving force DF can be seen to evolve as time progresses from time a tl to a time tlOO by generally increasing, approaching a value "FSL".

[0051] The value FSL may, for example, be predetermined. The value FSL may, for example, correspond at least in part to the rollback force on the vehicle.

[0052] The method may comprise determining the value FSL.

[0053] The value FSL may be greater than or equal to the rollback force, for example. For example, the value FSL may correspond to the rollback force and to an offset with respect to the rollback force. This offset may allow, for example for additional security against rollback, for example in the event of wind blowing on the vehicle 1 in a downhill direction.

[0054] The vehicle may be configured to determine the value FSL, for example, based on torque(s) imparted to one or more of the vehicle's wheels through interactions of the wheel(s) and the ground/road surface. For example, the vehicle 1 may include a sensor 8 to detect the(se) torque(s). A so-called "rollback torque" may be determined based on one or more of the(se) torque(s). As a non-limiting example, the rollback torque may correspond to a sum of these torques. When the vehicle 1 generates sufficient braking torque and/or driving torque for overcoming or cancelling out the rollback torque, movement of the vehicle 1 down the incline may be avoided.

[0055] The braking torque may be modulated inversely to the evolution of the driving torque. By modulating the braking torque inversely to the evolution of the driving torque, it may be possible, for example, to reduce or avoid interference with desired acceleration that could be caused by the braking torque.

[0056] Plot 2B of Figure 2 shows a plot of the vehicle's braking force "BF" over the same period of time shown in Plot 2A. The braking force BF can be seen to be modulated as time progresses from time tl to tlOO so as to generally decrease from the value FSL, approaching a value of zero.

[0057] Upon comparison of Plots 2A & 2B, it may be seen that the braking force BF may be modulated to decrease when the driving force DF increases (see for example intervals tl-tlO & t80-tl00). This may be understood to be indicative of the corresponding braking torque being modulated to decrease when the corresponding driving torque increases. This may have, for example, an effect of allowing the driving force to contribute to immobilizing the vehicle.

[0058] Additionally or alternatively, the braking force BF may be modulated to increase when the driving force DF decreases (see for example interval tl0-t80). This may be understood to be indicative of the corresponding braking torque being modulated to increase when the corresponding driving torque decreases. Thus, for example, it may be possible to (re)immobilize the vehicle using the braking force if the driving force falters (as with an aborted launch and/or a stalled motor, for example).

[0059] For example, the braking force BF may be modulated based on the evolution in the driving force DF such that a sum of the braking force and the driving force is greater than or equal to the value FSL. This may have, for example, an effect of reducing the driving force necessary for overcoming the braking force during mobilization of the vehicle. Additionally or alternatively, this may, for example, allow for the vehicle to transition from immobilization to movement relatively smoothly when the driving force approaches and subsequently exceeds the value FSL. [0060] Plot 3A of Figure 3 shows a plot of driving torque DT for the vehicle 1 shown in

Figure 1 during a period from a time t2 to a time t200. This period may be entirely non-concurrent with the period shown in Figure 2.

[0061] When the driving force is provided by interaction of multiple drive wheels with the ground/road surface, the driving torque DT may be understood to correspond to a sum of the torques imparted to the drive wheels to obtain the driving force, for example. Distribution of the driving torque DT amongst said multiple drive wheels may be performed evenly or unevenly according to known techniques.

[0062] At time t2, the driving torque DT is represented as being negligible (or zero). [0063] Plot 3B of Figure 3 shows a plot of the vehicle's braking torque BT over the same period as shown in Plot 3A.

[0064] When the braking force is provided by multiple brakes acting on multiple wheels which are rotationally mobile with respect to one another, the braking torque BT may be understood to correspond to a sum of the torques imparted by the multiple brakes on the multiple wheels to obtain the braking force, for example. Distribution of the braking torque BT amongst said multiple wheels and/or amongst said multiple brakes may be performed evenly or unevenly according to known techniques.

[0065] At time t2, the braking torque BT is represented as being substantially equivalent to a value SL. The value SL may correspond to the rollback torque of the vehicle in the same manner as the value FSL corresponds to the rollback force of the vehicle. For example, if the value FSL is selected to be greater than the rollback force by a certain offset, the value SL may be selected to be greater than the rollback torque by a corresponding offset.

[0066] Comparison of Plots 3A & 3B reveals that the braking torque BT is being modulated inversely to the evolution of the driving torque DT during at least a portion of this period.

[0067] Plot 3C of Figure 3 shows a plot of the vehicle's drive component velocity "V" over the same period as shown in Plot 3A.

[0068] At time t2, the velocity V of the drive component is shown to be negligible (or zero). The vehicle may therefore be immobilized at this time.

[0069] As seen in Figure 1, the vehicle 1 may, for example, comprise means for determining the drive component velocity V. For example, the vehicle 1 may comprise a sensor 31 for measuring the speed of the drive wheel 3 and/or the drive axle.

[0070] The driving torque DT may correspond to a motor torque and a transmission capacity, for example. Accordingly, in addition to or as an alternative to the sensor 51 for measuring the driving torque DT directly described earlier, the vehicle 1 may comprise means for determining the driving torque on the basis of the motor torque and the transmission capacity, for example. [0071] The transmission capacity may be understood to represent a maximum torque deliverable by a transmission of the vehicle. For example, a disengaged clutch 6 may be considered to provide a lower transmission capacity than a fully engaged clutch, and a partially-engaged clutch may be considered to have a transmission capacity intermediate that of a disengaged clutch and a fully engaged clutch. An automatic and/or continuously variable transmission may have a transmission capacity that may be determined at least in part by slippage, for example. Regardless of the type of transmission 10 that may be provided in the vehicle 1, the transmission capacity may additionally correspond at least in part to a gear ratio between the motor and the drive component 5, for example, possibly in combination with the value SL.

[0072] The vehicle 1 may comprise, for example, a sensor 73 for measuring the motor torque of the motor 7. Additionally or alternatively, the vehicle may, for example, comprise means 9 to measure the transmission capacity, for example. For example, the vehicle may include a sensor 91 to measure a position of a clutch pedal 61, possibly in combination with a sensor 93 to detect a gear ratio provided by the transmission 10 of the vehicle.

[0073] Plot 3D of Figure 3 shows a plot of the vehicle's transmission capacity "TC" (for example clutch engagement) over the same period as shown in Plot 3A.

[0074] At time t2, the transmission capacity TC is shown to be negligible (or zero). This may correspond, for example, to a disengaged clutch, whereas a fully engaged clutch would have a "full" transmission capacity TC.

[0075] Plot 3E of Figure 3 shows a plot of motor torque "MT" over the same period as shown in Plot 3A.

[0076] Comparison of Plots 3D & 3E reveals an example of interplay between the transmission capacity TC and the motor torque MT in their respective contributions to the driving torque DT shown in Plot 3A.

[0077] At time t2, the motor torque MT is shown to be relatively low. This may correspond, for example, to an idle state of the motor (for example in the case of a heat engine) and/or to an operating state of the motor in which motor torque is not used for movement (for example to power vehicle accessories). However, since the transmission capacity TC is negligible (or zero) at time t2, the motor torque is not converted into a non-negligible driving torque DT at this time.

[0078] Plot 3F of Figure 3 shows a plot of motor input signal "MI" over the same period as shown in Plot 3A. The motor input signal may, for example, correspond to a signal used for maneuvering the vehicle. As an example, the motor input signal may correspond to accelerator pedal position.

[0079] As seen in Figure 1, the vehicle 1 may, for example, comprise means 11 for determining the motor input signal. For example, the vehicle may comprise a sensor 111 for measuring the position of an accelerator pedal 12 of the vehicle.

[0080] Returning now to Figure 3, at time t2, the motor input signal MI is shown as being negligible (or zero).

[0081] At time t2, an attempt to accelerate the vehicle is initiated. The motor input signal MI is therefore shown as increasing subsequent to time t2. The motor torque MT increases, for example in response to the increase in the motor input signal.

[0082] During an interval from time t2 to time tB, the transmission capacity TC increases, allowing a portion of the motor torque MT to be converted into driving torque DT. At time tB, the transmission capacity is shown as having a value "TP", which may correspond to a "biting point" for a clutch, for example, where the transmission capacity meets or exceeds the motor torque.

[0083] During this same interval, the driving torque DT is shown as increasing, for example in response to the increased availability of motor torque MT and/or the increased transmission capacity TC.

[0084] During this same interval, the braking torque BT is inversely modulated relative to the evolution in the driving torque DT. Accordingly, the braking torque BT is shown as decreasing during this interval.

[0085] During this same interval, however, the vehicle remains immobilized (drive component velocity V remains negligible or zero), because the driving force corresponding to the driving torque DT is unable to overcome the braking force corresponding to braking torque BT, possibly in combination with environmental phenomena (such as rollback force, for example), to mobilize the vehicle.

[0086] Subsequent to time tB, the braking torque BT and possible environmental phenomena (such as rollback force, for example) may be transmitted back to the motor (for example as a disturbance torque) to a significant enough degree to interfere with motor behavior (possibly leading to lugging and/or stalling, for example), and/or reduce vehicle occupant comfort and/or cause excessive wear to one or more vehicle components.

[0087] The vehicle may be configured to determine the likelihood of one or more of these phenomena occurring. For example, the vehicle may comprise means for determining a state and/or behavior of the motor. For example, as seen in Figure 1, the vehicle 1 may comprise a motor speed sensor 75, possibly in combination with one or more of the sensors described earlier herein.

[0088] Returning now to Figure 3, subsequent to time tB, the motor torque MT is represented as comprising a reference motor torque "RMT", corresponding to the motor input signal MI, and the driving torque DT is represented as comprising an input reference driving torque "IRDT", corresponding to the reference motor torque in view of the transmission capacity TC.

[0089] If the reference motor torque RMT is not suitable for managing the disturbance torque and accelerating the vehicle, a motor assist signal may be provided to adjust the motor torque MT. In this way, the motor torque may correspond, for example, to a combination of the motor input signal MI and the motor assist signal.

[0090] At time tB, the driving torque DT (and possibly the input reference driving torque IRDT) is (are) shown to be less than the value SL. Thus, in view of the transmission capacity TC, it may be determined that the motor torque MT (and possibly the reference motor torque RMT) at time tB may be unsuitable for managing the disturbance torque and accelerating the vehicle.

[0091] During an interval from time tB to a time tA, the motor input signal MI and the transmission capacity TC are shown to continue to increase, albeit relatively gradually. Accordingly, the reference motor torque RMT and the input reference driving torque IRDT are shown during this interval to undergo relatively gradual changes.

[0092] During this same interval, however, the motor assist signal is applied. The motor torque MT is thus shown as diverging from the reference motor torque RMT by an amount "MB", and the driving torque DT is also shown to diverge relative to the input reference driving torque IRDT in a corresponding manner, in view of the transmission capacity TC, by an amount "DB". The motor torque MT is shown increasing relatively rapidly as the motor assist signal is applied to supplement the motor input signal MI, and the driving torque DT is shown increasing rapidly relative to the input reference driving torque IRDT.

[0093] The method may comprise determining the value MB and/or the value DB. [0094] During this same interval, the motor assist signal may be based at least in part on an amount "DH" by which the input reference driving torque is inferior to the value SL. The amount DH may correspond, for example to an inclination of the vehicle and/or the velocity V of the drive component of the vehicle. The vehicle may be configured to determine the amount DH, for example.

[0095] The vehicle may, for example, be configured to determine an amount "MH" by which the motor torque MT may be increased relative to the reference motor torque RMT in order to increase the driving torque DT by the amount DH, in view of the transmission capacity TC. As seen at time tA, increasing the motor torque MT by the amount MH relative to the motor assist torque (MB = MH at time tA, for example) allows for the driving torque to be increased relative to the input reference driving torque IRDT by the amount DH (DB = DH at time tA, for example). Accordingly, at time tA, the driving torque DT is shown reaching the value "SL".

[0096] During this same interval, the braking torque BT continues to be reduced, for example, as a result of inverse modulation with respect to the input reference driving torque IRDT. Although Figure 3 shows the braking torque BT as being inversely modulated, subsequent to tB, with respect to the input reference driving torque IRDT, it is also contemplated to inversely modulate the braking torque with respect to the driving torque DT (for example as determined by the vehicle), or as a combination of the driving torque and the input reference driving torque.

[0097] During this same interval, the drive component velocity V remains negligible (or zero), since the driving torque force corresponding to the driving torque DT may be unable to overcome the braking force corresponding to the braking torque BT, possibly in combination with environmental phenomena (such as rollback force, for example) to mobilize the vehicle.

[0098] Subsequent to time tA, the motor assist signal may be based at least in part on an amount "MS", which may correspond at least to managing the disturbance torque, for example. The vehicle may, for example, be configured to determine the amount MS as a function of one or more of the following: the transmission capacity TC (and/or a rate of change thereof), the value SL (and/or the amount MH and/or the amount DH), the velocity V of the drive component. The contribution of the amount MS of the motor torque MT, in view of the transmission capacity TC, to the driving torque DT is represented as an amount "DS". The vehicle may be configured to determine the value DS based at least in part on one or more of the following: the transmission capacity TC (and/or a rate of change thereof), the value SL (and/or the amount MH and/or the amount DH), the velocity V of the drive component. [0099] Additionally or alternatively, the vehicle may be configured to calculate a value "ST", which may correspond to a sum of the values SL and DS, for example. When the driving torque DT is determined to be not equal to the value ST or not within a predetermined range of the value ST, the motor torque MT may be adjusted so that the driving torque approaches the value ST, for example.

[0100] The relative contributions of amounts MS and MH on the motor torque MT are shown, respectively, as vertical separation distances between a dashed line and each of the motor torque MT and the reference motor torque RMT in Plot 3E.

[0101] During an interval from time tA to time tR, the motor input signal MI and the transmission capacity TC are shown to continue to increase, albeit relatively gradually. Accordingly the reference motor torque RMT and the input reference driving torque IRDT are shown during this interval to undergo relatively gradual changes.

[0102] During this same interval, however, the motor torque MT is shown to continue to diverge from the reference motor torque RMT as application of the motor assist signal continues, such that the amount MB of the divergence approaches a relatively constant offset with respect to the reference motor torque at or around time tR. The driving torque DT is also shown to continue to diverge from the input reference driving torque IRDT, such that the amount DB of the divergence approaches a relatively constant offset with respect to the input reference driving torque at or around time tR. [0103] During this same interval, the braking torque BT continues to be reduced until becoming negligible (or zero) at or around time tR. Although this is shown as occurring simultaneously with the amount MB reaching a relatively constant offset with respect to the reference motor torque RMT and/or with the amount DB reaching a relatively constant offset with respect to the input reference driving torque IRDT, it may be understood that the braking torque BT becomes negligible (or zero) non-concurrently with this/these event(s).

[0104] The drive component velocity V becomes non-negligible (the vehicle becomes mobile) as the driving force corresponding to the driving torque DT begins to overcome the braking force corresponding to the braking torque BT, possibly in combination with environmental phenomena (such as rollback force, for example).

[0105] During an interval from time tR to a time tS, the motor input signal MI and the transmission capacity TC continue to increase relatively gradually. Accordingly the reference motor torque RMT and the input reference driving torque IRDT are shown during this interval to undergo relatively gradual changes. [0106] At time tS, the input reference driving torque IRDT is shown to reach the value SL. Although this is shown as occurring simultaneously with the transmission capacity TC reaching full engagement, it may be understood that the two may occur non- concurrently with one another. [0107] During an interval from time tA to time tS, the motor assist signal MI may be based the amount MS in combination with the amount MH, for example. As time progresses during this interval, the amount MH (and/or the amount DH) may decrease as the input reference driving torque IRDT approaches the value SL. To preserve the relatively constant offset of amount MB with respect to the reference motor torque RMT (and/or the relatively constant offset of amount DB with respect to the input reference driving torque IRDT), the amount MS (and/or the amount DS) may increase. [0108] Additionally or alternatively, during this same interval, the amount DB may correspond at least in part to a combination of the amount DH and the amount DS. [0109] Subsequent to time tS, the motor assist signal may be based on the amount MS, since the input reference driving torque IRDT is no longer inferior to the value SL. Accordingly, the amount MB may correspond to MS and/or the amount DB may correspond to DS.

[0110] As an option, a motor assist factor may be provided, for example, to attenuate the motor assist signal in response to one or more triggers. [0111] For example, a trigger may correspond to an abandonment of the acceleration maneuver. Thus, for example, the motor assistance may be prevented from perpetuating an undesired maneuver. As an example, attenuation triggered by the abandonment of the acceleration maneuver may be relatively abrupt (on the order of less than 1 second, or less than 0.5 seconds, or less than 0.1 seconds, for example). [0112] For example, such a trigger may include detection of the braking torque BT increasing and/or exceeding a predetermined level B1 subsequent to time tB. For example, the vehicle may include a brake input sensor (such as a sensor on a brake pedal of the vehicle), and be configured to determine whether the brake pedal position corresponds to a braking torque BT that satisfies the trigger. [0113] Additionally or alternatively, such a trigger may include detection of the transmission capacity TC decreasing or falling below a predetermined level "TX" subsequent to time tB and/or time tA. For example, the vehicle may include a clutch engagement sensor (such as a sensor on a clutch pedal of the vehicle), and be configured to determine whether the clutch pedal position corresponds to a transmission capacity TC that satisfies the trigger. As an example, the value TX may correspond to a value intermediate to the value TP and full engagement of the clutch. [0114] Additionally or alternatively, such a trigger may include detection of the motor input signal MI falling below a predetermined value Ml. For example, the vehicle may include a motor input sensor (such as a sensor on an accelerator pedal of the vehicle), and be configured to determine whether the accelerator pedal position corresponds to a motor input signal that satisfies the trigger.

[0115] For example, a trigger may correspond to a successful conclusion of the acceleration maneuver. For example, the attenuation may proceed as the drive component velocity V increases beyond a predetermined level VI.

[0116] Plot 4A of Figure 4 shows a plot of driving torque DT during a period from a time t3 to a time t300. This period may be entirely non-concurrent with the period shown in Figure 2.

[0117] Although this period may additionally or alternatively be entirely non-concurrent with the period shown in Figure 3, the relationship between driving torque DT, motor torque MT and transmission capacity TC described with regard to Figure 3 may be understood to be applicable to Plots 4A-4C of Figure 4.

[0118] The description of the driving torque DT during the interval from time t2 to time tB in Figure 3 is also applicable to the driving torque DT shown in Plot 4A for the interval from time t3 to time tB.

[0119] Moreover, in the interest of simplicity, the driving torque DT during the interval from t3 to tB shown in Plot 4A can be considered identical to the driving torque DT during the interval from t2 to tB shown in Figure 3.

[0120] As seen with Figure 3, the driving torque DT in Plot 4A is shown subsequent to time tB as comprising an input reference driving torque IRDT, related to the motor input signal, and as diverging from the input reference driving torque during application of a motor assist signal so as to reach the value SL at time tA.

[0121] Moreover, in the interest of simplicity, the driving torque DT during the interval from tB to tA shown in Plot 4A can be considered identical to the driving torque DT shown during the interval from tB to tA in Figure 3.

[0122] As seen with Figure 3, the input reference driving torque IRDT in Plot 4A is shown to reach the value SL at time tS. [0123] Moreover, in the interest of simplicity, the reference input driving torque IRDT shown in Plot 4A can be considered to be identical to the reference input driving torque IRDT shown in Figure 3.

[0124] Plot 4B of Figure 4 shows a plot of a motor assist factor "AF" during the same period as shown in Plot 4A.

[0125] At time t3, the motor assist factor AF is represented as having a value of 1. When the motor assist factor AF has such a value, the motor assist signal may be applied at full scale. During the interval from time t3 to time tB, the motor assist factor AF is shown being maintained substantially at the value of 1.

[0126] Subsequent to time tB, the motor assist signal is applied.

[0127] During the interval from time tB to time tA, the motor assist factor AF continues to be maintained substantially at the value of 1. The driving torque DT changes rapidly, reaching the value SL at time tA.

[0128] During the interval from time tA to time tR, the motor assist factor AF is reduced. Although the reduction is shown as being performed gradually, it is also contemplated to provide substantially abrupt changes in the motor assist factor AF. Additionally, although the rate of reduction is shown evolving relatively gradually during this interval, it is also contemplated for the rate of reduction to evolve in a substantially abrupt manner.

[0129] Plot 4C of Figure 4 shows a plot of drive component velocity V during the same period as shown in Plot 4A. As with Figure 3, the drive component velocity V is shown in Plot 4C as being negligible (or zero) prior to time tR and as increasing beyond the predetermined level VI thereafter.

[0130] Moreover, in the interest of simplicity, the evolution of the drive component velocity V during the intervals from t3 to tR, and from tR to t300 in Plot 4A can be considered to be identical, respectively, to the evolution of the drive component velocity V during the intervals from t2 to tR and from tR to t200 in Figure 3.

[0131] Returning to Figure 4, it can be seen that, during the interval from time tR to time tS, the motor assist factor AF continues to be reduced. Although the reduction is shown as being performed at a relatively constant rate, it is also contemplated for the rate of reduction to be variable. Comparison of Plots 4B & 4C reveals that, as an example, the motor assist factor AF may be modulated inversely to the velocity of the drive component V of the vehicle during this interval. [0132] During this same interval, the driving torque DT is represented in Plot 4A as diverging non-negligibly from a unitary assistance reference driving torque "UADT", which corresponds to the amount of driving torque DT obtainable for an assist factor AF of 1 (in view of the transmission capacity), and approaching the input reference driving torque IRDT.

[0133] As an example, the driving torque DT may be approximately halfway between the unitary assistance reference driving torque UADT and the input reference driving torque IRDT when the motor assist factor AF has a value of approximately 0.5.

[0134] Although the driving torque DT is shown in Plot 4A as being approximately halfway between the unitary assistance reference driving torque UADT and the input reference driving torque IRDT when the input reference driving torque reaches the value SL, it is understood that these events may occur non-concurrently from one another.

[0135] During an interval from time tS to a time tE, the drive component velocity V continues to increase. While the drive component velocity V continues to increase, the motor assist factor AF continues to decrease, eventually becoming negligible (or zero) at time tE. Accordingly, the driving torque DT is shown during this interval to continue diverging from the unitary assistance reference driving torque UADT and approaching the input reference driving torque IRDT.

[0136] The driving torque DT may, for example, be made to approach the input reference driving torque IRDT so as to be approximately tangent to the input reference driving torque IRDT at time tE. This may, for example, be obtained by causing the motor assist factor AF to approach a value of zero in a tangential manner at time tE. It is also contemplated, however, for the driving torque DT to be non-tangential in its approach to the input reference driving torque IRDT.

[0137] At time tE, the driving torque DT and the input reference driving torque IRDT are shown to converge. Since the input reference driving torque IRDT is superior to the value SL at this time, the cessation of motor assistance does not necessarily lead to a deceleration of the drive component. Accordingly, the drive component velocity V is shown continuing to increase subsequent to time tE.

[0138] Additionally or alternatively, for example, a trigger may correspond to a failure of the acceleration maneuver. For example, such a trigger may include detection of one or more motor behaviors, such as stalling and/or lugging, for example (such as through measurements of motor torque and/or motor speed), or one or more precursors thereto. Additionally or alternatively, such a trigger may include detection of the drive component velocity V falling below a predetermined level V2 (possibly subsequent to exceeding the value VI). The value of V2 may correspond, for example, to a combination of the motor torque and transmission capacity. As an example, attenuation triggered by the failure of the acceleration maneuver may be relatively abrupt. Additionally or alternatively, such a trigger may also lead to reintroduction of modulating the braking torque inversely to the driving torque DT, for example.

[0139] Additionally or alternatively, a trigger may correspond to an inability to detect one or more of the aforementioned triggers.

[0140] As an option, attenuation of the motor assist signal may be overridden in one or more circumstances. An example of this is presented in Figure 5.

[0141] Plot 5A of Figure 5 shows a plot of driving torque DT during a period from a time t4 to a time t400. Plots 5B & 5C of Figure 5 respectively show plots of motor assist factor AF and drive component velocity V during the same period as Plot 5A. This period may be entirely non-concurrent with the period shown in Figure 2.

[0142] Although this period may additionally or alternatively be entirely non-concurrent with the period shown in Figure 3, the relationship between driving torque DT, motor torque MT and transmission capacity TC described with regard to Figure3 may be understood to be applicable to Figure 5.

[0143] Although this period may additionally or alternatively be entirely non-concurrent with the period shown in Figure 4, the relationship between the driving torque DT, drive component velocity V, motor assist signal, and motor assist factor AF described with regard to Figure 4 may be understood to be applicable to Figure 5.

[0144] In the interest of simplicity, the driving torque DT during the interval from t4 to tB shown in Plot 5A can be considered identical to the driving torque DT during the interval from t3 to tB shown in Figure 4.

[0145] As seen with Figure 4, the driving torque DT in Plot 5A is shown subsequent to time tB as comprising an input reference driving torque IRDT related to the motor input signal, and as diverging from the input reference driving torque during application of a motor assist signal so as to reach the value SL at time tA.

[0146] Comparison of Plots 4A & 5A reveals that, at time tA, the input reference driving torque IRDT in Plot 5A is further from the value SL than the input reference torque IRDT in Plot 4A. Accordingly, it may be understood that the motor assist signal applied during the interval from time tB to time tA interval in Plot 5A may be different (for example more intense) than the motor assist signal applied during this interval in Plot 4A.

[0147] As seen with Figure 4, the driving torque DT in Plot 5A is shown during the interval from time tA to time tR to continue increasing. However, in contrast with the interval from tA to tR shown in Plot 4A, the input reference driving torque IRDT shown during this interval in Plot 5A is shown as stabilizing at time tR.

[0148] Additionally, during this same interval, Plot 5B shows the motor assist factor AF as being maintained at a value of 1. It may thus be understood that no trigger has occurred during this interval.

[0149] Despite the faltering input reference driving torque IRDT visible in Plot 5A at time tR, Plot 5C shows the drive component velocity V as being negligible (or zero) prior to time tR and as increasing thereafter beyond the predetermined value VI. Accordingly, it may be understood that the motor assist signal may be adjusted based on the motor input signal MI and/or input reference driving torque IRDT and/or transmission capacity TC in order to provide a given driving torque DT.

[0150] During an interval from time tR to a time tF, the driving torque DT is shown as continuing to increase, despite the fact that the input reference driving torque IRDT is not shown as increasing. During this same interval, the drive component velocity V is shown as increasing, and the motor assist factor AF is shown as decreasing.

[0151] Subsequent to time tF, the driving torque DT is shown as diverging from a unit assist driving torque UADT, similar to what was described subsequent to time tR in Plot 4.

[0152] As seen in Figure 5, during an interval from time tF to a time tM, the input reference driving torque IRDT continues to falter, and is shown inferior to the value SL at time tM.

[0153] During this same interval, the drive component velocity V continues to increase. The motor assist factor AF is shown as decreasing as attenuation is allowed to proceed. Accordingly, the driving torque DT is shown during this same interval as approaching the input reference driving torque IRDT.

[0154] At or around time tM, the driving torque DT has a value of SL.

[0155] During an interval from time tM to time tE, the driving torque DT is shown as diverging from an overall attenuation reference driving torque "ADT", which corresponds to the driving torque DT obtainable in view of the uniform assist reference driving torque UADT, the input reference driving torque IRDT, and the motor assist factor AF when applied to the amount MB in view of the motor input signal corresponding to the input reference driving torque IRDT.

[0156] During this same interval, the motor assist factor AF is shown to continue decreasing, eventually reaching a value of zero at time tE. Accordingly the overall attenuation reference driving torque ADT is shown approaching the input reference driving torque IRDT during this interval, and meeting it by time tE.

[0157] During this same interval, instead of decreasing below the value SL, as with the overall attenuation reference driving torque ADT, the driving torque DT remains greater than or equal to the value SL. This may be accomplished, for example, by applying the motor assist factor AF to the amount MS (in view of the motor input signal corresponding to the input reference driving torque IRDT) without applying it to the amount MH (in view of the motor input signal corresponding to the input reference driving torque IRDT).

[0158] In contrast with time tA, at time tM, the likelihood of motor behaviors such as lugging and stalling may be relatively low, since drive component velocity V is relatively high (for example greater than the level V2), despite the driving torque DT having a similar value at the two times.

[0159] With the driving torque DT being maintained in this way, the drive component velocity V during this interval is shown to continue increasing. Although the drive component velocity is shown to stabilize at or around time tE, it may be understood that this could also occur non-concurrently with the motor assist factor AF reaching zero.

[0160] Subsequent to time tE, the input reference driving torque IRDT is shown as increasing, whereas the driving torque DT is shown as being maintained substantially at the value SL. At time tS, the input reference driving torque reaches the value SL. [0161] Since the driving torque DT remains at the value SL during this interval, the drive component velocity V is shown as being relatively stable.

[0162] Subsequent to time tE, the input reference driving torque IRDT exceeds the value SL. Since the motor assist signal is no longer applied, the driving torque DT and input reference driving torque IRDT are equivalent to one another, and the driving torque exceeds the value SL as well.

[0163] In addition, it is contemplated, as an option, to attenuate the motor assist signal when one or more of the foregoing triggers is/are not determinable. For example, as seen in Figures 4 & 5, if the vehicle is unable to determine the speed V of the drive component or its relationship to the speed value VI and/or the speed value V2, and/or, as seen in Figure 3, if the vehicle is unable to determine the motor input signal MI or its relationship to the value Ml, and/or if the vehicle is unable to determine the transmission capacity TC or its relationship to the value TX, and/or if the vehicle is unable to determine the brake input signal or the relationship between the corresponding braking torque BT and the value Bl.

[0164] Although the foregoing discussion of the motor assist signal describes its application for the purposes of supplementing the motor input signal MI (for example so that the motor torque MT exceeds the motor reference torque RMT), it is also contemplated, in addition or as an alternative, for example, for the step of adjusting the motor torque MT to include applying the motor assist signal to diminish the motor input signal in order to reduce the motor torque (for example so that the motor torque falls below the motor reference torque).

[0165] Although the described embodiments were provided as different exemplary embodiments, it is envisioned that these embodiments are combinable or, when not conflicting, the features recited in the described embodiments may be interchangeable. Moreover, the features recited in the described embodiments are not inextricably linked to one another, unless such a linkage is clearly indicated between two given features. [0166] Throughout the description, including the claims, the term "comprising a" should be understood as being synonymous with "comprising at least one" unless otherwise stated. In addition, any range set forth in the description, including the claims should be understood as including its end value(s) unless otherwise stated. Specific values for described elements should be understood to be within accepted manufacturing or industry tolerances known to one of skill in the art, and any use of the terms "substantially" and/or "approximately" and/or "generally" should be understood to mean falling within such accepted tolerances.

[0167] Although the present disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure.

[0168] It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.

Claims

1. A method of accelerating a vehicle (1), comprising modulating a braking torque (BT) of the vehicle based on an evolution in a driving torque (DT) delivered to a drive axle of the vehicle such that the braking torque is modulated inversely to the evolution of the driving torque.

2. The method of claim 1, comprising increasing the braking torque (BT) in response to the driving torque (DT) decreasing, and/or reducing the braking torque in response to the driving torque increasing.

3. The method of claim 1 or 2, wherein the braking torque (BT) is modulated based on the evolution in the driving torque (DT) such that a sum of a braking force (BF), corresponding to the braking torque, and a driving force (DF), corresponding to the driving torque, is greater than or equal to a first predetermined value (FSL, SL).

4. The method of claim 3, comprising determining the first predetermined value (SL) based on a rollback force on the vehicle, the rollback force corresponding to a rollback torque on the drive axle.

5. The method of claim 3 or 4, the driving torque (DT) corresponding to a motor torque (MT) and a transmission capacity (TC), the method comprising determining whether, in view of the transmission capacity, the driving force (DF) is equal to or within a predetermined range of a second predetermined value (ST), greater than or equal to the first predetermined value (FSL, SL), and adjusting the motor torque, when the driving force is determined to be not equal to or not within the predetermined range of the second predetermined value, so that the driving force approaches the second predetermined value.

6. The method of claim 5, the transmission capacity (TC) corresponding at least to an engagement factor of a clutch (6) of the vehicle (1).

7. The method of claim 5 or 6, comprising determining the second predetermined value (ST) based on one or more of the following: the transmission capacity (TC), the first predetermined value (SL), a speed (V) of the drive axle.

8. The method of any of claims 5-7, the motor torque (MT) corresponding to a motor input signal (MI) and a motor assist signal, the step of adjusting the motor torque including applying the motor assist signal to supplement the motor input signal in order to increase the motor torque.

9. The method of claim 8, the step of adjusting the motor torque (MT) including applying the motor assist signal to supplement the motor input signal (MI) in order to increase the driving torque (DT) such that the driving force increases to or above the first predetermined value (FSL, SL).

10. The method of any of claims 5-9, the motor torque (MT) corresponding to a motor input signal (MI) and a motor assist signal, the step of adjusting the motor torque including applying the motor assist signal to diminish the motor input signal in order to reduce the motor torque.

11. The method of any of claims 8-10, comprising attenuating the motor assist signal in response to one or more of the following: a speed (V) of the drive axle meeting or exceeding a predetermined first speed value (VI), the motor input signal (MI) falling below a predetermined first motor value (Ml) or being not determinable, the transmission capacity (TC) falling below a predetermined first transmission value (TX) or being not determinable, a brake input signal being detected at or above a predetermined first brake value (Bl) or being not determinable, a predetermined motor behavior being detected.

12. The method of claim 11, comprising increasing the braking torque (BT) in response to the speed (V) of the drive axle falling below a second speed value (V2).

13. The method of claim 12, wherein the step of increasing the braking torque (BT) in response to the speed (V) of the drive axle falling below the second speed value (V2) is performed subsequent to an onset of attenuation of the motor assist signal.

14. The method of any of claims 5-13, wherein the steps of determining whether the driving force is equal to or within a predetermined range of the second predetermined value (ST) and adjusting the motor torque (MT) are performed when the transmission capacity (TC) exceeds a third predetermined value (TP).

15. The method of claim 14, comprising determining the third predetermined value (TP) based on one or more of the following: the first predetermined value (SL), a gear ratio between the motor (7) and the drive axle.

16. A vehicle (1) configured to carry out a method according to any of the preceding claims.

17. The vehicle (1) of claim 16, comprising one or more of the following: means for determining a state and/or behavior of a motor (7) of the vehicle, means for determining a speed of a drive axle of the vehicle, means (9) for determining a transmission capacity and/or a gear ratio between the motor and drive axle, means (11) for determining a motor input signal, means for determining a rollback torque.